public virtual CellAreaContext create_context ()
Creates a CellAreaContext to be used with this for all purposes.
CellAreaContext stores geometry information for rows for which it was operated on, it is important to use the same context for the same row of data at all times (i.e. one should render and handle events with the same CellAreaContext which was used to request the size of those rows of data).
a newly created CellAreaContext which can be used with this.